25 触媒的不斉水素化を鍵反応とする光学活性リグナン類の合成(口頭発表の部)  [in Japanese] 25 Synthesis of Optically Active Lignans Using Catalytic Asymmetric Hydrogenation as a Key Reaction  [in Japanese]

We found that neutral and cationic rhodium (I) complexes of (S,S)- or (R,R)-MOD-DIOP (1 or 2) showed very high enantio-selectivity in the catalytic asymmetric hydrogenation of α-arylidenesuccinic acid half-esters (3). The optically active α-aryl-methylsuccinic acid half-esters (4) obtained are useful inter-madiates for the synthesis of optically active lignans. Total syntheses of (+)-collinusin (7), (-)-deoxypodophyllotoxin (9), and (+)-neoisostegane (14) were achieved using asymmetric hydrogenation catalyzed by the rhodium(I) complex with (S,S)-MOD-DIOP (2) as a key reaction. Thus, the absolute configurations of natural (+)-collinusin (7) and (+)-neoisostegane (14) were determined to be (R) and (M,6R,7R), respectively. The present asymmetric hydrogenation can provide a practical method for the synthesis of various optically active lignans.